1. Field of the Invention
The present invention relates generally to a drill and drill chuck assembly for connection with a flexible drive shaft, and, more particularly, to such a drill and chuck assembly especially adapted for use in medical implant drilling, (e.g. drilling into shoulder or hip bones) to provide axial and rotational restraint for the drill as well as providing a construction which is readily disassembled for sterilization of its parts.
2. Description of Related Art
In a number of different medical implant operations, an important step is the drilling of holes into bones for receiving screws to secure implanted sockets, and the like. In this context, it is important, due to the operation environment, that a drill bit and its motor drive be interconnected by a flexible member so that the surgeon can drill holes in a hip or shoulder bone, for example, at various angles. It is not unusual, because of restricted access, that the surgeon must drill at 90 degrees or more relative to the drill motor. Also, as a final step in the drilling process, the drill is reversed in direction and pulled out of the bone. Of course, it is highly important that the drill not become disengaged from the flexible shaft chuck since this could require surgical removal which could become complicated. Clearly, it is highly desirable that the drill cannot become inadvertently disengaged from the flexible shaft by either axially applied force or rotational torquing.
One approach in the past has been to weld or braze the drill directly to the flex shaft. However, in this case when the drill gets dull it is then necessary that the entire device be replaced which, of course, is costly.
In another known apparatus, a cross pin is brazed onto the drill bit shank and a mating notch is formed on the chuck collet. The drill is installed with the cross pin engaged into the mating notch and a sleeve threaded over the two parts to retain the cross pin. Disadvantages of this apparatus are that the drill shank has to be cross drilled and of course the pin brazed in place with close centering on the cross pin. The medical community does not find this completely satisfactory in that it particularly requires completely removing the sleeve to replace the drill bit.
In a still further known approach, a quick disconnect type of assembly has clocking teeth, and a multiplicity of parts that do not readily disassemble for sterilization.
In yet another known device, a threaded hole on the end of a fitting for the flexible shaft mates with a thread on the end of the drill shank. This device has the undesirable disadvantage in that the drill could disengage from the flexible shaft thereby leaving the drill bit in the patient and disassembly of the drill bit cannot be achieved by hand and may require extra tools.